Abstract
The hydrology of coastal lakes differs significantly from that of inland water bodies due to the influence of the neighboring sea. Observed climatic changes are expected to enhance the effect of the sea on coastal lake ecosystems, which makes research on sea–lake interactions even more significant. In this study, on the basis of maximum annual and monthly values of water level, dependencies among the water levels of six lakes located along the southern coast of the Baltic Sea in Poland, and the Baltic Sea water levels were analyzed. First, the Spearman rank correlation and the linear regression method were applied. Then, selected copulas were used to find joint distributions of the studied time series. In the next stage, the degrees of synchronous and asynchronous occurrences of maximum water levels in lakes and the sea were calculated. The study revealed that correlations between the maximum annual water levels in coastal lakes and in the Baltic Sea in the selected gauge stations were very strong and statistically significant. These results were confirmed by a synchronicity analysis carried out with the help of a copula function. The highest relationship was detected in the case of Lake Resko Przymorskie (correlation coefficient 0.86, synchronicity 75.18%), while the lowest were observed in Lakes Jamno (0.62 and 58.20%, respectively) and Bukowo (0.60 and 56.82%, respectively). The relation strength between maximum water levels of the sea and coastal lakes may increase in the future due to sea level rises caused by climate warming.
Highlights
A total of 7081 Polish lakes have a surface area of more than one hectare [1]
The results of this study provide a more precise view of connections between water levels in the Baltic Sea and the analyzed coastal lakes
This paper presents the possibility of applications of synchronicity analyses in the analysis of the dependency of maximum water levels in coastal lakes on sea water levels, which can contribute to an increase in the level of water management in coastal areas
Summary
A total of 7081 Polish lakes have a surface area of more than one hectare [1]. A large group of those are coastal lakes characterized by complex water circulation due to the intensive supply of river waters from inland areas and the impact of sea waters [2].Unlike in the case of the remaining parts of Poland, lakes in the coastal zone in the north of the country are characterized by the occurrence of hydrological phenomena and processes that do not occur in inland areas, e.g., the phenomenon of backwater and sea water intrusion, wind-induced blocking of lake water outflows, and the phenomenon of water rise, which are observed on the Baltic coast in the period of winter storms [3].Lakes located at the interface of land and sea, i.e., areas different in terms of both physical and chemical properties, develop a specific geoecosystem in which the direction of physical, chemical, and biological processes depends on which of the two environments has a stronger impact at a given moment [4]. A large group of those are coastal lakes characterized by complex water circulation due to the intensive supply of river waters from inland areas and the impact of sea waters [2]. Unlike in the case of the remaining parts of Poland, lakes in the coastal zone in the north of the country are characterized by the occurrence of hydrological phenomena and processes that do not occur in inland areas, e.g., the phenomenon of backwater and sea water intrusion, wind-induced blocking of lake water outflows, and the phenomenon of water rise, which are observed on the Baltic coast in the period of winter storms [3].
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